NHS health trusts have reported almost 20,000 incidents of pest infestation in hospitals over the past two years, it emerged today.

Outbreaks have included rats in maternity wards, wasps and fleas in neo-natal units and maggots in patients’ slippers, says newspaper reports.

But the Government dismissed suggestions that the problems were linked to the spread of hospital-acquired infections such as MRSA and said the threat to patient safety was “negligible”.

The details – released under the Freedom of Information Act – were obtained by the Tories, who contacted all 171 NHS trusts in England.

Of the 127 which responded, almost all were said to have experienced some problems.

The Calderdale and Huddersfield NHS Foundation Trust, which runs Huddersfield Royal Infirmary, reported that it had logged 212 visits by pest control officers between January, 2006, and April this year.

The Mid Yorkshire Trust, which includes Dewsbury District Hospital, said it had had weekly inspections by the pest experts.

There were almost 20,000 reports of pest problems while seven out of 10 trusts said they had called in pest control officers more than 50 times since January, 2006.

The figures showed that 80% of NHS trusts reported problems with ants, 66% with rats and 77% with mice.

Cockroaches were said to have been reported at 59% of trusts, fleas or other biting insects at 65% and bed bugs at 24%.

A further 6% of trusts reported infestations of maggots. Many of the problems were said to have been in clinical areas.

Health Minister Ivan Lewis said it was up to NHS trusts to ensure that hospitals were clean and safe for patients.

But he insisted that, so far, there was little evidence of any threat to patient safety.

He added: “The use of pest control is seen as good, proactive management.

“The Health Care Commission has confirmed that health concerns around pest control have, to date, been negligible.